/Engine/Source/Runtime/Slate/Public/Framework/Application/SlateApplication.h
a handle for the existing or newly created virtual slate user. This is handy when you need to create virtual hardware users for slate components in the virtual world that may need to be interacted with with virtual hardware.
[TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [FSlateVirtualUserHandle](API\Runtime\Slate\Framework\Application\FSlateVirtualUserHandle) > FindOrCreateVirtualUser ( int32 VirtualUserIndex )